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Dimple die scratches skin surface

Michael Burbidge

Michael Burbidge

Well Known Member
I'm having a really difficult time preventing the dimple die from scratching the surface of my HS skins as I move it over from hole to hole while using my C-Frame to dimple. I've built a table for my C-Frame so that the skin is supported as I'm dimpling. I lift the skins as I move it, or so it seems. But I guess not enough. There is still a light scratch between holes. In any event, the skin is just lightly dragging against the tip of the dimple. But the soft alclad surface is no match for the hard tip of the dimple die.

Do I have a bad dimple die? Does anyone have any tips on how to prevent scratching the surface. These are very light scratches in the alclad. It's very annoying!

Someone should make plastic or nylon tipped dimple dies.
 
You can try polishing the tip of your dimple die a little better, but in all honesty these scratches are inconsequential. You're going to have 1000s more by the time you are done. Then you're going to take a Scotch-Brite pad or sandpaper to the plane before painting it anyway.
 
Sounds like you are using some kind of "C" frame device.

Do you have any kind of flat surface "Table top" around the unit??

A couple of pieces of soft foam, a couple of inches to the sides of the die will keep the skins above the die, you need foam that will hold the skin up, yet compress when you form the dimple.

May take a bit of trial and error, practice on scrap.

This worked for me, using a DRDT2------with a "bang-on-it" unit, you will probably need to use one hand to hold the skin down when you hit the plunger.

Good luck.
 
Mine too

I agree with Guy. My dimple die does the same thing if I let it contact the skins at all as they move to the next hole. The scratches are so light that they are nothing to worry about and by the time you paint the aluminum you won't even notice them.
 
Happens to everyone

It is no problem they will buff out or if you paint the aircraft you'll never know they were there.

Build on
 
Reverse the dies?

Can you work it the other way round... with the "pin" of the die on top?

Don't use the return spring, and hold up the C-frame set as you move the skin around... gently let the set down so that the "pin" falls in the hole... then whack it!...:)

This way, you are moving the skin over the polished "innie" die.

If you leave the return spring on... you will have made a good skin punch...:mad:

gil A
 
Turn it over

I agree with Gil. Turn the dimple die over so the male half is on top.
Aaron
 
AMURRAY said:
I agree with Gil. Turn the dimple die over so the male half is on top.
Aaron
Click to expand...

I think this would make the process take much longer. With a C frame you would have to be really careful to make sure the male die went into the drilled hole or you'll find an extra hole :eek:

This would be a little easier with a DRDT-2 (which I'm fortunate to have and will never part with, at least until my 9a is finished) because you don't have to whack anything with a hammer.

Just don't worry about these little "mars"; they'll buff out. If you don't like those marks just wait until you start backriveting stiffeners on your very thin rudder skins! The back rivet plate will leave little mars as well.
 
Boy, there's no way I'd ever turn those dimple dies around, at least if you use the C-frame tool as they come...with the little spring and O ring holding the stem slightly above the work.

Having the "male" poking through the hole is the only confirmation that things are lined up properly.

I'm familiar with the problem you describe, and it is unsightly but as others have stated, inconsequential. Still, you should be able to minimize it by lifting the work off the die more rather than dragging it across it.
 
Change the die around

I have to say I agree with the builders that changed the dies around, particularly of you are working alone. I did the HS and the first wing the normal way with the male on the bottom and the spring loaded rod on top and found it very awkward to move the skin without it getting marked and then holding the skin and wacking with the mallet.
If you change the orientation and remove the spring you can easily slide the skins to position with one hand and then let the rod side "drop" into the hole (and the female die) and then wack with the mallet.
Net result for me at least was easier, faster, less marks and better dimples (no spring resistance and bounce as the die is in contact with the skin when wacked).
I actualy noted this on my web site as a tip as it made so much difference.

The joy of building is that everyone can have a valid (but different) opinion.

YMMV
 
Not what I said...

Bob Collins said:
Boy, there's no way I'd ever turn those dimple dies around, at least if you use the C-frame tool as they come...with the little spring and O ring holding the stem slightly above the work.

Having the "male" poking through the hole is the only confirmation that things are lined up properly.

I'm familiar with the problem you describe, and it is unsightly but as others have stated, inconsequential. Still, you should be able to minimize it by lifting the work off the die more rather than dragging it across it.
Click to expand...

Bob... that wasn't what I said....

Don't use the return spring, and hold up the C-frame set as you move the skin around... gently let the set down so that the "pin" falls in the hole... then whack it!...

This way, you are moving the skin over the polished "innie" die.

If you leave the return spring on... you will have made a good skin punch

see my previous post #6

gil A
 
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I agree with Gil but get the DRDT2

Hi Michael,
I had the same thing going on with my emp and I reversed the dies and it solved the problem, but I have a DRDT2. IMHO the C-Frame unit is as inconsistent as the user can be. Some people can wack that thing consistely and I think others may wack the he!! out of it. I honestly think that if you hit it hard enough that you can over stress the material. Yes you could over stress it also with the DRDT2, but it would be a lot harder to do since you can set the depth of the dies.
Get the DRDT2 and you will be glad you did. No noise at all...boy that makes all the difference in the world.
Jim King
7A Wings
 
az_gila said:
Can you work it the other way round... with the "pin" of the die on top?

Don't use the return spring, and hold up the C-frame set as you move the skin around... gently let the set down so that the "pin" falls in the hole... then whack it!...:)

This way, you are moving the skin over the polished "innie" die.

If you leave the return spring on... you will have made a good skin punch...:mad:

gil A
Click to expand...

After going through the same thing Michael, I did what Gil said and this is how I dimple now. If you do it this way though, don't get in a rush and "drop" the shaft with the male die on it onto your skin or it leaves a nasty ding, even from a height of about only an inch. Ask me how I know.

I love my C-frame, and personally don't think the DRDT-2 is worth the extra dough. And yes, I have used one.
 
DaX said:
I love my C-frame, and personally don't think the DRDT-2 is worth the extra dough. And yes, I have used one.
Click to expand...

If noise is an issue, you might change your mind. Also, when you get to the larger sheets, you may also have a different opinion.
 
I went with the DRDT-2, and put the male die on top. It's rather easy for me to hold the handle partway down to shorten the gap between the dies, and then lift the skin slightly to bring it up to the male die and mate them, then dimple while keeping just enough up pressure on the skin to prevent it from slipping off the male die. With the male on the bottom, I was tired of "hunting" for the hole with the die that you can't see, and found that I was scratching the skin a lot more than I ever do now with the male die on top, where you can visually line it up quickly. In any event, the scratches are just cosmetic. I've found that the alclad is so soft I actually mar it with the sharpies. When I remove the sharpie marks with laquer thinner, you can plainly see the letters/marks "buffed" into the alclad from the felt tip of the Sharpie.
 
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Try using some Scotch Removable magic tape #811. Place a strip over the line of holes that you want to dimple and use something pointy and sharp to pre-punch the tape at each hole. The tape can be reused a few times. I've dimpled all the skin on my 7A w/o any scratches. There is some extra effort but the preparation is worth it. Not an original idea, but suggested by a good friend.
 
scratching skin with dimple die

I wonder, does a scotchbrite pad or orbital sander scratch the skin when preping for painting?
Yikes, and you're worried about a die scratch? If you've never seen a plane properly preped for painting you'd better have the nitro tabs on the ready.
Mike H 9A/8A
 
Mike, I errored in my first posting. I use Van's riveting tape #685 to protect the skin while dimpling. It doesn't have adhesive in the center - makes it a bit easier to manage. Then I use the Scotch tape to secure the rivets while riveting either with the rivet gun or squeezer - no surface marks after setting the rivets.
 
All these marks are COMLETELY inconsequential and all efforts to avoid them are a waste of time and lead to long build times. 0.02 cents

That said I feel like an idiot for never considering reversing the dimple dies!!! I am 1/4 through dimpling my wings and can't wait to get home and try this. Not to avoid minor mars but to speed things up as hunting for the male point beneath the skin is a pain.

I have no trouble being quick and achieving fine results solo with a c-frame. I'll duel anyone with a drdt any time.:p
 
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